google maps - Add a button with onclick event in infowindow -

i trying add button onclick event in infowindow of google map api v3

        var cont = "<div><h4><b>transformer</b></h4><label>name: </label>"+this.transformername.charat(0).touppercase()+this.transformername.substring(1)+"<br><label>site no: </label>"+this.siteno+"<br><label>substation no: </label>"+this.substationno+"<br><label>transformer no: </label>"+this.unitno+"<br><button onclick='voltagemodel()'>voltagetrend</button></div>";     console.log(cont);     infowindow.setcontent(cont); 

but onclick event not firing kindly help

try

  <button onclick='voltagemodel();'>voltagetrend</button> 

you missed ;